Industrial robots of this type with parallel kinematics are used to move, position and/or process an object in space. They comprise a robot base arranged in a fixed position and a moveable carrier element for receiving a gripper, a tool or a machine element. At least two actuating units are connected at their one end to the robot base and at their other end to the carrier element. Each actuating element is moved by a drive assigned to it which is arranged on the robot base. A movement of the actuating units causes a movement of the carrier element. For example, a gripper for picking up an object or a tool for processing an object or a machine element such as a bearing or a gearbox can be arranged on the carrier element. To this end the carrier element is equipped with a receiver for a gripper, a tool or a machine element. The gripper, the tool or the machine element arranged on the carrier element can be moved in several dimensions in space in a targeted manner by means of the coordinated movement of the driven actuating units. The actuating arms effect a spatial parallelogram guidance of the carrier element. The parallel kinematics resulting from this enable a rapid and precise movement of the carrier element and of the gripper, tool or machine element arranged thereon. This movement is a translatory movement of the carrier element. If the industrial robot is equipped with three actuating units, the translatory movement is in three directions in space. The movement has three degrees of freedom and can be described in a coordinate system with x, y and z axes. If the industrial robot is equipped with two actuating units, the translatory movement is in two directions in space. In this case the movement has two degrees of freedom and can be described in a coordinate system with x and z axes. In addition to this translatory movement of the carrier element, a torque can be generated by a further drive on the robot base and transmitted to a gripper, tool or machine element arranged on the carrier element. This is a rotational movement and hence a further degree of freedom. This movement serves not to position the gripper, tool or machine element in space but instead to move the gripper, tool or machine element itself, for example opening and closing the gripper or turning the tool or machine element. If the industrial robot is equipped with three control arms, a rotational axis transmitting the torque from the drive to a gripper, tool or machine element on the carrier element is referred to as a fourth axis.
Such robots include delta robots, for example. These are equipped with at least two control arms as actuating units. The actuating or control arms comprise an upper and a lower arm section which are connected to one another in a moveable manner. Each of the upper arm sections is driven by an actuating arm drive, for example a motor-gear unit. The drives are arranged on the robot base. The movement of the upper arm sections is transferred via the lower arm sections to the carrier element. Each lower arm section has two parallel rods or struts running in the longitudinal direction of the arm section, which are moveably connected at their one end to the associated upper arm section and at their other end are moveably connected to the carrier element.
In addition to delta robots, industrial robots with parallel kinematics also include cable robots. Cable robots are equipped with cables as actuating units. Each cable is connected by its one end to a drive. The drives take the form of rotation or linear drives which determine the free length of the cables by winding and unwinding on a shaft connected to a cable end or by advancing or retracting a push rod connected to a cable end. At their end facing away from the drive, the cables are connected to a carrier element for a gripper or a tool. It must be ensured thereby that the cables are tensioned. The gripper or the tool arranged on the carrier element can be moved in several dimensions in a targeted manner by means of the coordinated movement of the drives.
A gripper, a tool or a machine element arranged on the carrier element can additionally be actuated via a pneumatic, hydraulic or electric drive. Sensors for monitoring and controlling the gripper, tool or machine element can also be arranged on the carrier element. For this purpose, hydraulic, pneumatic, electric or optical supply lines are routed from the robot base to the carrier element. The supply lines are used for the transport of compressed air, a pressure medium, electric current or light. Light can be necessary, for example, for a sensor arranged on the gripper or on the tool. The supply lines thereby connect the robot base to the carrier element freely and without guidance or they are guided along the actuating units or along the transfer device.
An industrial robot of this type with actuating units in the form of control arms is known, for example, from EP 250 470 A1.
Known industrial robots with parallel kinematics have the disadvantage that only one rotational degree of freedom is available for the movement of a gripper, tool or machine element arranged on the carrier element. Only one-dimensional rotational movements can therefore be executed with the gripper, tool or machine element.